Gas chromatography was applied for determination of the amounts of propionic and butyric acids in the medium produced by Propionibacterium acnes. The organism was incubated in Peptone-Yeast extract-Glucose medium containing 0.017 mEq/ml of tributyrin and various amounts of Coptidis Rhizoma at 37 degrees C for 24 to 96 hr. The amount of butyric acid produced by the lipase was reduced parallel with that of propionic acid resulted from the growth of P. acnes in the medium. These facts were also confirmed by counting the cell numbers of P. acnes. Furthermore, any lipase-negative colonies were not observed on the Kishishita's Lipase Medium. These findings indicate that Coptidis Rhizoma inhibits growth of P. acens and anti-lipase activity of the drug against the organism is resulted from the fact.